1. Field of the Invention
The invention relates to the prediction of defects in the manufacture of products. More specifically, the invention relates to the prediction of wrinkling in the forming of sheet metal when using hydroforming or other like processes, as well as suggesting design solutions to the wrinkling problem.
2. Description of the Related Art
Traditionally, engineering or design groups would encounter and resolve sheet-metal wrinkling problems during hydroforming by trial and error. The tool designer would initially design the parts details per parameters handed down from product development staff. Next, through a process known in the art as “tool try-out,” the designs are then manufactured into sample parts, or instead virtually analyzed by metal forming specialists to determine the formability or feasibility of the design. In the event the part winkled on manufacture, or if preliminary analysis predicted possible wrinkling, the part would be completely redesigned and the process repeated. The defective parts produced may in some circumstances be reworked to remove the wrinkles by hitting the part with a mallet (hereinafter referred to as “hand forming”). In other circumstances the defective part may be used as is in the wrinkled state if allowed by design constraints.
Simulations have been used by artisans for analyzing wrinkling problems. These processes, however, are accurate only when the design exhibits a tendency to wrinkle severely. These conventional simulations are less accurate for minor hand-formable wrinkles, i.e., wrinkles that can be smoothed with minor manual rework. The simulation software currently used does not provide any recommendations to prevent failure due to wrinkling. Instead, this software can only be used to analyze the effect without deciphering the cause of the wrinkling. Identifying the cause of failure and possible corrective action is the responsibility of the analyst. Because of this, the analyses are iterative, and each run of the analysis can take anywhere between a couple of hours to days to complete. These conventional procedures are inefficient, uneconomical, and extend product development cycle times significantly.